The Vietnamese government is quietly celebrating the fact that John McCain, the "Manchurian candidate" they brainwashed and programmed to seize power in the United States is only a few steps away from their goal. His chief rival, George W Bush, who plans to free all drug offenders if elected, has a new strategy to woo Latino voters: he is doubling his normal tip in Mexican restaurants.

As the campaign for the Republican and Democrat nominations reaches its likely climax in California and New York tomorrow, the satirical rumour mills have been grinding even more energetically.

It is not surprising that the notion of Mr McCain as a brainwashed tool of the communists should have a certain frisson. John Frankenheimer's 1962 film The Manchurian Candidate explored the idea of an American hero of the Korean war who had been programmed by the communists to return to the US and kill a politician. Starring Lawrence Harvey, Frank Sinatra and Janet Leigh, the film caused waves at a time when the US was recovering from its McCarthyite anti-communist witch-hunts. The wicked rumour that Mr McCain, a prisoner of the Vietnamese for five and a half years, was the new "Manchurian candidate" has been given its biggest airing by his own supporters, who have publicised it as an example of how dastardly some opponents can be in spreading such obvious nonsense.

Mr Bush was an early victim of the dirty rumour mills. A website, gwbush.com, which purported to be his, claimed that in his first year in office he would empty the jails of the country's 400,000 drug offenders. Citing the fact that one in nine children in the US has a parent in jail, he was said on the site to want to become "the president who gave those kids their parents back".

"Recreational drug users - like I used to be - are serving life sentences because dealer friends made up stories to get a lighter sentence," says "Mr Bush" on the bogus website. "If this were happening in China, we'd probably start bombing them for human rights violations. We have to let these people go."

Mr Bush's attempts to win the Latino vote prompted The Onion, a Wisconsin-based satirical newspaper and website, to run the story: "Bush reaches out to Hispanic community with generous tip."

The Onion records that "Bush extended the hand of friendship to the nation's Hispanic community by leaving a larger-than-customary tip for waiter Ramon Gonzalez after eating at La Galeria, a trendy Chula Vista bistro". The Onion, which has 1m readers, suggested that Mr Bush's "$20 gratuity on a bill of $83.42, working out at 24%, is the largest tip the Hispanic community has ever received from a Republican presidential candidate". Mr Bush was quoted as saying: "It is my way of acknowledging the many valuable things Hispanics bring to the table - from appetisers to drinks to main courses."

The Republican frontrunner was also mocked after a rally in Michigan last week, when a Canadian television reporter told Mr Bush that he had won the endorsement of the Canadian prime minister, Jean Poutine. Mr Bush was flattered and told the reporter: "I'm honoured... He understands that I want to ensure our relationship with our most important neighbour to the north of us, Canadians, is strong. We will work closely together."

Alas for Mr Bush, the real Canadian prime minister is Jean Chrétien - while Poutine is a high-calorie, fast-food French-Canadian dish of chips covered in gravy and cheese curd. The "journalist" was the Canadian comedian Rick Mercer who operates in a similar way to Britain's Ali G and often pokes fun at Americans' ignorance of Canada. Mr Bush's gaffe was gleefully transmitted in Canada last week. He was targeted after he failed to identify the leaders of India and Pakistan in interviews.

But if Mr Bush continues to run, comedians may be redundant anyway. He is, after all, the "compassionate conservative" who last week gave the go-ahead to execute a great-grandmother in Texas.

As satirist Tom Lehrer said when Henry Kissinger won the Nobel peace prize: "Who needs satire?"